Please
read this document – it provides a central pillar for all things. Including
helpful links to the other docs plus useful snippits…
All documents, code, schematics, firmware etc are offered as an aid to the experienced constructor to allow them to build their own division controller.
I offer no warranty either express or implied, i.e. you build and operate this device at your own risk.
In building and operating this device you accept that there may be bugs or other problems both with the hardware, its associated firmware and documentation that may cause it to function in a manner that could possibly cause injury.
None of the documentation, hardware design or software either in whole or part may be used for commercial purposes.
Any re-distribution of this material must contain the original material in its original form; no charge may be made for its distribution.
For feature list and device description see Manual.htm.
· Manual.htm - Instructions for operation of controller (V2.0).
· PartsList.htm - Parts list.
· Construction Notes.htm - Rough guide to constructing device on veroboard (stripboard).
· Construction.pps - Rough guide to constructing device on PCB.
· Circuit Diagram v2.0.jpg - Circuit diagram…
· Firmware2.0.hex - V2.0 firmware for 18F452 (see below for How to Program the 18F452).
· Rotary2.0.LYT - Proteus PCB layout file. (Freeware version of proteus is available at http://www.proteuslite.com/ download and install this, it should allow you to view and print the PCB layout)
· PCB 2.0.bmp - PCB layout in .BMP format.
· PCB Overlay 2.0.bmp - PCB component overlay in .BMP format.
· Keypad template.doc - keypad overlay template suitable for use with ‘Farnell’ sourced keypad.
Building on a PCB is easiest, however the circuit works perfectly well constructed on stripboard. Decide which you want to use and if using stripboard then have a read of the construction notes otherwise view construction.pps.
You’ll need a pre-programmed 18f452 microcontroller; you can program this yourself with the provided firmware or get someone else to do it (see below How to Program the 18f452).
Most parts are readily available and substitutable, see the parts list.
Finally with pre-programmed PIC, misc components, PCB (or stripboard), a printout of the circuit diagram and pcb overlay then warm up your soldering iron and get to work.
This controller requires a suitable stepper motor and stepper motor driver to function. It generates ‘step’ and ‘direction’ on two wires, which connect to suitable stepper drivers. To facilitate a wide range of drivers the controller allows the polarity of the step and direction signals to be flipped.
The choice of stepper driver and motor will depend on what you want to use it for. A 16 inch table being used under power for cutting will need a much bigger stepper/driver than a 4 inch being used solely for division. For division using 4, 6 or 8 inch tables the commonly available 2 amp(ish) Chinese sourced steppers and cheap stepper drivers do an admirable job. If using these a cheap laptop power supply can be used to drive both the controller and the stepper/driver.
I’ve found Motion Control Products and Arc Euro Trade in the U.K to be good source of cheap steppers/controllers. A search for ‘Stepper Motor’ on eBay is also more than likely to turn up a few possibilities.
The active or enable line is set whenever the table is moving and released when it stops. Its polarity can be swapped in setup.
If you use this to enable/disable your stepper driver note that in microstep mode it’s possible your stepper controller will release the motor allowing it to move to the nearest full step. This will introduce an accumulative error every time the motor stops. Unless you’re sure of its operation I’d recommend ignoring this line.
Provided are two limit switch inputs – one stops clockwise movement the other anticlockwise. They can be connected together but then you’ll need an override switch adding since the table will be unable to move in the opposite direction to release the switch. These operate by pulling to ground.
Note there is no isolation provided – if you’re going to use them in a nasty environment then they should be connected via a buffer/opto isolator etc.
The sense and acknowledge lines provide means of connecting to other equipment. Acknowledge provides an signal (open collector) to indicate that the table is moving. (In program mode it needs to be manually set). Sense provides a means of triggering movement, this line needs to be pulled low, held for a short time then released, this triggers movement to the next position (in program mode this allows the program to continue past Wait Sense).
A ‘pendant’ switch could be connected to the sense line for remote operation.
By cross connecting sense and ack lines between two controllers they can be made to perform complex operations – i.e. automatic gear cutting etc.
If you’re asking then it’s safe to assume you don’t have a PIC programmer…
The previous version was 1.1, the big jump to 2.0 is mainly due to the new programming mode. In summary the changes are:-
I try to be a fairly helpful chap (as of Jan 1st 2008) so if you’ve any queries just send them to mailto:steve@worldofward.com?subject=Rotary table controller query.
Have fun!
